Stacked Against All Odds – Mine Tailings Stacks

The night is waning into dawn, and the air is thick with smoke and desperate moves. The mine mill is still churning off in the distance. The odds are against you – what to do?

Such is the thought of a bedeviled tailings planner, knowing that tomorrow more tailings will come, capacity will decrease, and the process engineer will ask again, “Where has all my water gone?”

The days of traditional hydraulic tailings disposal may be nearing an end, or at least, the image of tailings disposal is changing significantly. To the benefit of our tormented tailings planner, new and developing technologies may provide the means to economically alter the behaviour of slimes. We must recognize though, that like most things, the change is transitional, gradual, and likely not to be adopted by everyone, everywhere. Mike Davies provides an insightful overview of the evolving tailings management practices at this link.

We should incorporate new tailings terminology, like stacked tailings, in our vocabulary. Tailings.info provides this definition of dry and wet stacked tailings created using a filter press:

Dewatering tailings to higher degrees than paste produces a filtered wet (saturated) and dry (unsaturated) cake that can no longer be transported by pipeline due to its low moisture content. These filtered tailings are normally transported by conveyor or truck, deposited, spread and compacted to form an unsaturated tailings deposit (Davies and Rice 2001). This type of tailings storage produces a stable deposit requiring no retention bunding and is referred to as ‘dry stack’.

Stacks may be constructed with filter pressed tailings, paste tailings, or others like flocculated or centrifuged tailings. For the truly adventurous, the technologies can be combined for optimal dewatering. Stacks require smaller footprints and can be compacted, trafficked, and reclaimed much easier than traditional tailings facilities. Some of the world’s leading suppliers of mineral processing technology can offer help – FLSmidth, Westech, Paste Thick Associates, Outukumpu, and Delkor are just a few.

So if you’ve ever dreamed of building massive sand castles on mines, consider stacks as a viable alternative to traditional hydraulically placed tailings. The tailings planners and process engineers of tomorrow will thank you.